The invention relates to marine drive water pumps, and particularly addresses problems with frozen water pumps.
In a marine drive when the unit is frozen in water, or water otherwise freezes in the pump, the pump impeller fails when the starter rope is pulled or the engine cranked because the impeller and its mounting and/or bonding arrangement is not strong enough to crush the ice.
A marine drive water pump is typically a rotary vane positive displacement pump having a pump driveshaft, a drive hub around the driveshaft and keyed thereto to rotate therewith, and a plurality of flexible vanes extending radially outwardly and bonded to the hub along an annular vane base portion, for example as shown in Kiekhaefer U.S. Pat. No. 2,466,440 and Bloemers et al U.S. Pat. No. 4,392,779. Various metals have been used for the drive hub, including brass and stainless steel. Plastic hubs have also been used, for example injection molded nylon, and which may also be reinforced, such as with glass or other random chopped fibers.
Metal hubs are susceptible to rubber adhesion failures due to galvanic action at the bond interface with the vanes. Non-metallic plastic hubs solve the adhesion problem, and are strong enough for normal duty. However, plastic hubs crack and split if abused or subjected to higher torsional loading, which occurs when the pump assembly freezes full of ice.
The present invention addresses and solves the above noted problems. The invention solves the problem of hub splitting due to torsional loading, while still retaining rubber bond adhesion to the hub. The invention thus provides both of the above noted previously incompatible results. The invention applies filament winding technology to a marine drive water pump impeller, which application has been found to afford significant performance improvements. The invention enables exceptional strength in the desired direction, namely circumferential hoop strength, without sacrificing bond adhesion strength.